1. Field of the Invention
The present invention relates to a dicyanoimidazole compound derivative and a magenta toner for color electrophotography, colored resin, colored molded resin member and a resin color filter incorporating the dicyanoimidazole compound derivative.
2. Description of the Prior Art
To impart a color to toners for color electrophotography, thermoplastic resins, thermosetting resins, color filters, etc., various pigments and dyes are used according to respective uses and purposes.
For example, organic pigments are commonly utilized since they are excellent in color fastness to light and heat resistance and offers a wide variety of colors, particularly distinct colors.
Also, oil-soluble dyes and dispersion dyes are used to obtain toners with distinct color for color electrophotography and colored resins with transparency and gloss since they are highly soluble in resin.
Moreover, a toner for color electrophotography incorporating a sublimational dye makes it possible to obtain images which are high in both chromaticity and lightness.
In color electrophotography, to obtain full-color images by superposing toner images of yellow, magenta and cyan colors, the three subtractive primaries, it is necessary for each toner to have a good spectral property and transparency for color reproduction. Transparency is also required in toners used for color electrophotography on sheets for overhead projector (hereinafter referred to as OHP). It should also be noted that these toners are required not to be prone to discoloration, fading or bleeding due to light or heat.
A number of means have been proposed to meet such requirements. For example, Japanese Patent Publication Open to Public Inspection Nos. 295069/1987, 155555/1987 and 217465/1989 respectively disclose a color toner incorporating various oil-soluble or dispersion dyes, a magenta toner incorporating a Rhodamine dye, and a magenta toner incorporating an anthraquinone dispersion dye. Also, color toners with improved light transmittance are proposed in Japanese Patent Publication Open to Public Inspection Nos. 52560/1987 and 75645/1987.
With respect to colored resins or colored molded resin members, transparency is often demanded as well as color fastness to light, bleeding resistance and resistance against heat during molding.
Optical color filters needed for television cameras, liquid crystal televisions, flat panel displays on computers, etc., must be good in spectral property and transparency.
Examples of red pigments for optical filters include those disclosed in Japanese Patent Publication Open to Public Inspection No. 278569/1989.
Although color filters are often produced by dyeing a dyable film of gelatin, casein, polyvinyl alcohol, or the like on a transparent resin or glass base plate with a pigment having a given spectral property by printing, sublimational transfer, etc., it is desirable to color the resin itself from the viewpoint of durability.
Of such conventional coloring agents, organic pigments often fail to satisfy the requirement for transparency because they are almost insoluble in resin. On the other hand, oil-soluble dyes and dispersion dyes are prone to discoloration, fading, and bleeding. As for sublimation dyes, they often show re-sublimation over a long period, which in turn may cause image density reduction or staining; therefore, their application is limited to auxiliary use for the above-mentioned purposes.
Therefore, none of the toners for color electrophotography, colored resins, colored molded resin members and color filters which incorporate a conventional coloring agent are said to fully satisfy the essential requirements described above.